岩の多孔性によって制御される小惑星の微細レゴリット産生

S Cambioni^1,2, M Delbo³, G Poggiali⁴

¹Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. saveriocambioni@email.arizona.edu.

Nature

|October 7, 2021

まとめ

ベヌやリウグーのような有孔の炭化小惑星では稀です岩は断片ではなく圧縮されるからですこれらの地形は,多孔性の少ない石の小惑星ではより一般的です.

科学分野:

惑星科学
小惑星の表面プロセス
レゴリット物理学

背景:

宇宙船のミッションでは石質の小惑星の凝固されていないレゴリスを観測した.
望遠鏡のデータでは,炭酸性小惑星 (例えば,ベヌ,リウグー) のレゴリットが示唆されている.
観測された微小化の過程は,ベンヌとリウグの広範囲な規則石の欠如と対照的です.

研究の目的:

炭酸性小惑星の広範囲な規則石の欠如の理由を調査する.
小惑星ベヌの岩の多孔性と亜センチメートルの粒子の量との関係を調べるため
異なる小惑星のレゴライトの有無を推測する.

主な方法:

小惑星ベヌからの宇宙船のデータ分析
地元の亜センチメートル粒子の豊富さと岩石の多孔性との相関分析.
岩石の断片化と熱破裂に関する研究室での実験と比較

主要な成果:

半センチメートルの粒子の豊富さと岩の多孔性との間には逆の相関関係があることが判明しました
ベヌの多孔性岩は衝突によって圧縮され断片化されていません
熱破裂は,より密度の高い岩石と比較して遅いです.

結論:

凝固していない亜センチメートルの粒子の蓄積は,多孔性の高い小惑星の表面で妨げられます.
レゴライトの毛布は,岩の多孔性により,炭酸性小惑星では珍しく見られる.
レゴリットの地形は,多孔性の低い岩石小惑星では一般的であると予測されています.

さらに関連する動画

07:22

Author Spotlight: Unraveling the Role of Earthworms in Enhancing Mineral Weathering for CO2 Removal

Published on: November 10, 2023

3.8K

07:54

Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas

Published on: April 3, 2018

8.4K

関連する概念動画

01:20

Porosity and Absorption of Aggregate

453

Aggregates contain pores of varying sizes; while some are completely enclosed within the particles, others open onto the surface, allowing water to penetrate. The porosity of aggregates is a major factor contributing to the overall porosity of concrete, given that aggregates constitute about three-quarters of concrete's volume.
When all pores in an aggregate are filled with water, the aggregate is considered saturated and surface-dry. If left in dry air, water will evaporate until the...

453

01:18

Porosity in Cement Paste

261

The porosity of concrete is a measure of the void spaces within its structure. These spaces impact its strength and durability significantly. When water and cement interact, a chemical reaction called hydration creates a semi-solid paste. This paste includes combined water, making up approximately 23% of the cement's dry mass, and gel water, which fills minuscule voids known as gel pores, accounting for about 28% of the cement gel volume.
The balance of water to cement in the mix is...

261

01:23

Pore Size Distribution

238

In concrete, the pore size distribution significantly influences the material's properties. Capillary pores, markedly larger than gel pores, form a vast network within partially hydrated cement paste, reducing the concrete's strength and increasing its permeability. This heightened permeability leads to a greater risk of damage from environmental factors like freeze-thaw cycles and chemical attacks, with the extent of vulnerability also being tied to the water-to-cement ratio.
Adequate...

238

01:25

Shape and Texture of Coarse Aggregate

313

Aggregate shape is classified based on the relative sharpness or roundness of the edges and corners. This classification includes categories like rounded, angular, elongated, and flaky, each with specific characteristics. Rounded aggregates, fully shaped by attrition, are typical of river or seashore gravel, while angular aggregates, such as crushed rock, have well-defined edges. Aggregates that are elongated and flaky are less desirable, as they can reduce the workability and strength of...

313

01:16

Precipitate Formation and Particle Size Control

1.3K

In precipitation gravimetry, the precipitating agent should react specifically or selectively with the analyte. While a specific reagent reacts with the analyte alone, a selective reagent can react with a limited number of chemical species.
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...

1.3K

01:19

Specific Gravity of Aggregate

442

Aggregates typically contain pores, which can be either permeable or impermeable. Considering the pores in the aggregates, the specific gravity of aggregates is defined in three different forms, namely, bulk or gross specific gravity, apparent specific gravity, and absolute specific gravity.
Bulk or gross specific gravity is calculated by taking the ratio of the mass of aggregates in the saturated surface-dry state to the total volume that includes both the solids and the voids within the...

442

関連する実験動画